Problem: The grades on a language midterm at Gardner Bullis are normally distributed with $\mu = 80$ and $\sigma = 2.0$. Stephanie earned a $79$ on the exam. Find the z-score for Stephanie's exam grade. Round to two decimal places.
Explanation: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Stephanie's exam grade by subtracting the mean $(\mu)$ from her grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{79 - {80}}{{2.0}}} $ ${ z \approx -0.50}$ The z-score is $-0.50$. In other words, Stephanie's score was $0.50$ standard deviations below the mean.